My duckweed seems to be dying! After massive growth for three months and had roots hanging down about 1", now most of it looks white and no roots.

I recently had a problem with ammonia levels in tank and used a combination of ammonia-sorb, carbon, and water changes. The carbon was to remove medication I used in the tank. The ammonia level maxed out at .35 (combined ammonia + ammonium). My suspicion is the carbon removed some essential nutrients? Any suggestions?

My stem plants still are doing well, as are my swords.
I dosed today with Flourish comprehensive and have ecocomplete substrate. I removed the carbon and ammonia-sorb from my canister yesterday.

No expert but I think a few good size water changes to get the trace elements back in your tank should do the trick. We are talking about duckweed here which stays true to its name of weed, if your other plants are doing well then the duckweed should come back.

Agree; it is indeed odd to have duckweed--which many will refer to as a plant that cannot be killed--fail when other plants are thriving.

I have duckweed deliberately in one or two tanks, and I have noticed that it can go through periods of decline. Actually, most plants do similar. It could be a seasonal issue, needing a rest period (plants do), or changes to the water parameters or chemistry. Floating plants seem particularly sensitive to the latter.

The aquarist is one who must learn the ways of the biologist, the chemist, and the veterinarian.[unknown source]

Something we all need to remember: The fish you've acquired was quite happy not being owned by you, minding its own business. If you’re going to take it under your wing then you’re responsible for it. Every aspect of its life is under your control, from water quality and temperature to swimming space. [Nathan Hill in PFK]

Could be a significant shift in pH? The tank went from 7.6 (high ammonia) last week to it's current 7.0.

A shift in pH can cause plant changes (usually temporary), that's true; but 7.6 to 7.0 is not major--although crypts would likely melt at this. My tank pH fluctuates by about .3 or .4 every water change, but that doesn't seem to deter the duckweed.

More likely something affecting the water chemistry, and I think it just occurred to me.

Plants need ammonia, or rather ammonium, as their preferred source of nitrogen. Duckweed is a fast growing plant, and thus assimilates a lot more nutrients, ammonium included. The Ammonia Sorb may have removed so much ammonia that the duckweed was literally starved of nitrogen. I'm going from memory here, but I believe green plants turning white [as you mentioned] indicates nitrogen deficiency.

I tried to find info on Ammonia Sorb online, and can't. That in itself would cause me to never use this product. All I can find out is that it supposedly "removes" ammonia. Some products, like Prime, detoxify ammonia by changing it to ammonium, so the plants would actually benefit. But if the ammonia is actually being rempoved from the water, and in sufficient quantities, plant trouble could ensue.

Echinodorus (swords) take longer than faster-growing plants to show such effects, but within a week or two you may see issues with the swords.

I would certainly remove this product, and if ammonia continues to be a problem, use something that detoxifies it into ammonium. Though if i read correctly earlier, the ammonia issue is now gone.

The aquarist is one who must learn the ways of the biologist, the chemist, and the veterinarian.[unknown source]

Something we all need to remember: The fish you've acquired was quite happy not being owned by you, minding its own business. If you’re going to take it under your wing then you’re responsible for it. Every aspect of its life is under your control, from water quality and temperature to swimming space. [Nathan Hill in PFK]

Byron, thanks - I expect you are correct, as usual .
I have noticed my dwarf sword's newest leaves are pale. Hopefully, this will all reach equilibrium relatively soon. If it ain't the fish, it's the flippin' plants!

Byron, thanks - I expect you are correct, as usual .
I have noticed my dwarf sword's newest leaves are pale. Hopefully, this will all reach equilibrium relatively soon. If it ain't the fish, it's the flippin' plants!

New leaves on Echinodorus are frequently lighter green, quite pale; they darken as they grow. So that may not mean much. I would look more for existing leaves paling or yellowing. And if they do, they (those leaves) will not recover. New growth will be normal (once the issue is gone).

The aquarist is one who must learn the ways of the biologist, the chemist, and the veterinarian.[unknown source]

Something we all need to remember: The fish you've acquired was quite happy not being owned by you, minding its own business. If you’re going to take it under your wing then you’re responsible for it. Every aspect of its life is under your control, from water quality and temperature to swimming space. [Nathan Hill in PFK]